At least the absence of front brakes is authentic for a pre-1923 Rolls-Royce.
I'm told that at the time RR considered front brakes to be dangerous things since they enabled the driver to lock the front wheels!

It's been a very long time since this thread saw any action, but since the posts I made above I now believe that the rear tractor involved at Hixon was one of the Anderson-cabbed DT's, since photos have come to light which suggest the Anderson silhouette rather than the small cab silhouette.
I think that this narrows it down to one of three tractors, but I still would be interested in knowing which it was if anyone knows.

The protoype MH-8875 tractor, the unit used for the tank transporter bid, went via GEC Alsthom to ALE where it has given great service of many years. I believe that it has now been retired.
The new batch of six ALE Trojan tractor units were designed and built by ALE in-house at Hixon, Staffordshire. ALE bought six French Army surplus Unipower 8800 units with a view to upgrading them, but after assessing their suitability and condition decided to start from scratch (although it is rumoured that there are some parts of the ex-French units in the Trojans).
The design is in some ways an evolution of the MH-8875 and builds on the lessons learned from years of operating that pioneer unit, and is in many ways probably the vehicle Unipower would have built if the firm had survived.
The Trojan 8870 is the most powerful (and cleanest) prime mover ever to operate on British roads, and is the first such vehicle to have full CANbus-based multiple unit operation allowing the lead tractor to operate everything but the steering on helper units.
A remarkable and very impressive example of great British engineering!

If by "sand" you really do mean sand, then don't do it, it is illegal and dangerous for the reasons stated above.
If your question is more generic and by "sand" you mean any safe solid abrasive blast media, then personally I would not do it. The blast media has a tendency to get into every nook and cranny and I personally feel that the risk of something highly abrasive getting into bearings etc is simply too great. I do know that others however seal up openings etc and seem to have trouble-free results, but that is not something I would risk.
I am fortunate enough to have a wet-blast machine which produces virtually no abrasive dust, one of several advantages of wet blasting. Even so, it is not something I would consider..

That certainly doesn't look like any keying hammer that I have ever seen, and the shape makes it fundamentally unsuited to that task. A keying hammer has a long thin end in order to fit between the rail and chair, that headwould not fit. Having said that, I am sure that I have seen just such a hammer fairly recently but I can't remember where or when.
Back on the subject of "sand blasting" please remember that it is both illegal and very foolish to blast with sand or any other medium containing more than 1% free silica. This is due to the high risk of contracting silicosis, a truly awful debilitating illness with no cure. It is prohibited under the COSHH Regulations, 1999. You must use proper, intended-for-the-purpose blast media. It is also highly advisable (essential in the workplace) to use an air-fed full face or full head mask or shield.
Remember also that the paint you are blasting into airborne dust may contain lead and other evil health hazards.
If you can get hold of one, a wet blast machine will give better results, is more versatile, much cleaner, and almost dust free (and therefore healthier) than a dry blaster. The downside is that typically a wet blast machine is around ten times the price of a dry blast machine.
Blasting is a great timesaver and really useful technique, but you want to live long enough to enjoy the results of your endeavours.

I've just had a quick tally-up round the barn and found the rather startling total of four Monkey winches and three of the scarcer Wallaby winches!
Does this make me a bad person or just a weirdo?
I may have to investigate remanufacturing the various springs used on these winches. Most other parts are easy enough to refurbish but the springs tend to fail and are all oddballs.

So the changes should only affect vehicles built on HGV chassis, but who will determine and how will the issue be managed of deciding if a vehicle is in scope or not?
My Iron Fairy Six is Engineering Plant (it doesn't fit the Mobile Crane definition for various reasons even though it is a crane and is mobile) but to get it to an MOT would involve either a low-loader or about a day of driving a 12mph vehicle on A roads. It is not an HGV chassis, of course. Hopefully there will be no suggestion that a test will become needed.

A resurrection to a very old thread....
I was rather saddened to learn yesterday that the firm of Trewhella Brothers went into liquidation early in May 2017, bringing to an end another chapter of British engineering. I found it strangely reassuring that up until now it was possible to buy spares for the Monkey and Wallaby winches, along with the rope shorteners, fence wire strainers, and other top qualtiy Trewhella products. Sadly no more.
So another British engineering name bites the dust. Very sad.